1. Field of the Invention
This invention relates generally to the field of protein processing and protein signalling pathways and specifically to two novel proteins having distinct activities, which are derived from a common hedgehog protein precursor.
2. Related Art
Over the past decade, extracellular protein signals encoded by several gene families have emerged as central players in coordinating cell behavior and thus generating pattern during animal development. Members of the hedgehog (hh) gene family in particular are notable for their association with several well-studied patterning activities. In Drosophila, where hh was discovered and isolated, patterning functions include specification of positional identity within developing segments and appendages. In vertebrate embryos, function of the hh family member Sonic hedgehog (Shh) is associated with the patterning influences of notochord and prechordal plate mesoderm on spinal cord and brain, as well as on other surrounding structures. Shh expressed in mesoderm at the posterior margin of the developing vertebrate limb bud also plays a central role in controlling limb outgrowth and patterning. The patterning functions of hh proteins have been extensively studied (see Hammerschmidt et al. 1997 for a recent general review), and novel functions continue to emerge.